<template>
  <div class="gc-canvas" @click="reloadPic">
    <canvas
      id="gc-canvas"
      :width="contentWidth"
      :height="contentHeight"
    ></canvas>
  </div>
</template>

<script>
export default {
  name: "JGraphicCode",
  props: {
    length: {
      type: Number,
      default: 4
    },
    fontSizeMin: {
      type: Number,
      default: 20
    },
    fontSizeMax: {
      type: Number,
      default: 45
    },
    backgroundColorMin: {
      type: Number,
      default: 180
    },
    backgroundColorMax: {
      type: Number,
      default: 240
    },
    colorMin: {
      type: Number,
      default: 50
    },
    colorMax: {
      type: Number,
      default: 160
    },
    lineColorMin: {
      type: Number,
      default: 40
    },
    lineColorMax: {
      type: Number,
      default: 180
    },
    dotColorMin: {
      type: Number,
      default: 0
    },
    dotColorMax: {
      type: Number,
      default: 255
    },
    contentWidth: {
      type: Number,
      default: 136
    },
    contentHeight: {
      type: Number,
      default: 38
    }
  },
  methods: {
    // 生成一个随机数
    randomNum(min, max) {
      return Math.floor(Math.random() * (max - min) + min);
    },
    // 生成一个随机的颜色
    randomColor(min, max) {
      let r = this.randomNum(min, max);
      let g = this.randomNum(min, max);
      let b = this.randomNum(min, max);
      return "rgb(" + r + "," + g + "," + b + ")";
    },
    drawPic() {
      this.randomCode();
      let canvas = document.getElementById("gc-canvas");
      let ctx = canvas.getContext("2d");
      ctx.textBaseline = "bottom";
      // 绘制背景
      ctx.fillStyle = this.randomColor(
        this.backgroundColorMin,
        this.backgroundColorMax
      );
      ctx.fillRect(0, 0, this.contentWidth, this.contentHeight);
      // 绘制文字
      for (let i = 0; i < this.code.length; i++) {
        this.drawText(ctx, this.code[i], i);
      }
      this.drawLine(ctx);
      this.drawDot(ctx);
      this.$emit("success", this.code);
    },
    drawText(ctx, txt, i) {
      ctx.fillStyle = this.randomColor(this.colorMin, this.colorMax);
      let fontSize = this.randomNum(this.fontSizeMin, this.fontSizeMax);
      ctx.font = fontSize + "px SimHei";
      let padding = 10;
      let offset = (this.contentWidth - 40) / (this.code.length - 1);
      let x = padding;
      if (i > 0) {
        x = padding + i * offset;
      }
      // let x = (i + 1) * (this.contentWidth / (this.code.length + 1))
      let y = this.randomNum(this.fontSizeMax, this.contentHeight - 5);
      if (fontSize > 40) {
        y = 40;
      }
      var deg = this.randomNum(-10, 10);
      // 修改坐标原点和旋转角度
      ctx.translate(x, y);
      ctx.rotate((deg * Math.PI) / 180);
      ctx.fillText(txt, 0, 0);
      // 恢复坐标原点和旋转角度
      ctx.rotate((-deg * Math.PI) / 180);
      ctx.translate(-x, -y);
    },
    drawLine(ctx) {
      // 绘制干扰线
      for (let i = 0; i < 1; i++) {
        ctx.strokeStyle = this.randomColor(
          this.lineColorMin,
          this.lineColorMax
        );
        ctx.beginPath();
        ctx.moveTo(
          this.randomNum(0, this.contentWidth),
          this.randomNum(0, this.contentHeight)
        );
        ctx.lineTo(
          this.randomNum(0, this.contentWidth),
          this.randomNum(0, this.contentHeight)
        );
        ctx.stroke();
      }
    },
    drawDot(ctx) {
      // 绘制干扰点
      for (let i = 0; i < 100; i++) {
        ctx.fillStyle = this.randomColor(0, 255);
        ctx.beginPath();
        ctx.arc(
          this.randomNum(0, this.contentWidth),
          this.randomNum(0, this.contentHeight),
          1,
          0,
          2 * Math.PI
        );
        ctx.fill();
      }
    },
    reloadPic() {
      this.drawPic();
    },
    randomCode() {
      let random = "";
      // 去掉了I l i o O
      let str = "QWERTYUPLKJHGFDSAZXCVBNMqwertyupkjhgfdsazxcvbnm1234567890";
      for (let i = 0; i < this.length; i++) {
        let index = Math.floor(Math.random() * 57);
        random += str[index];
      }
      this.code = random;
    }
  },
  mounted() {
    this.drawPic();
  },
  data() {
    return {
      code: ""
    };
  }
};
</script>

<style scoped></style>
